Two-zone timepiece



March 3l, 1970 V w. w. MUTTER ETAL l v3,503,203

- Two-ZONE Tiummcn l Filed Nov. 15. 1967 i v2 shee'. :sneeL 1v @gne-@L Purme- Pow INVENTOR- United States Patent O 3,503,203 TWO-ZONE TIMEPIECE William W. Mutter, Paramus, and George P. Gruner, Ridgewood, NJ., assignors to Bulova Watch Company, Inc., New York, N.Y., a corporation of New York Filed Nov. '15, 1967, Ser. No. 683,393 Int. Cl. G04b 19/22 U.S. Cl. 5842.5 12 Claims ABSTRACT F THE DISCLOSURE A timepiece capable of displaying time in two zones and having two hour hands, one serving to indicate Greenwich mean time or time at a home base, the other to indicate time in a local zone, the local-time hand being adjustable in 30 increments in either direction independently of the first hour hand so that it may be shifted when entering a new time zone without -affecting the GMT or home-base time reading, incremental adjustment being effected by a planetary gear system whose sun gear is driven by the watch motor and whose planet carrier is linked to the local-time hand, the ring gear of this system being shiftable abruptly in either direction to effect a discrete one-hour change in the position of the local-time hand.

This invention relates generally to timepieces, and more particularly to a watch having two hour hands, one of |which serves to indicate Greenwich mean time or time at a home base, the other functioning to indicate time in a local zone and being incrementally adjustable when entering a new time zone without disturbing the setting of the first hand.

Greenwich mean time (GMT) or Universal Time, is the local mean time of the Greenwich meridian (longitude 0). The difference between standard time in any zone and GMT is equal to the longitude of the standard meridian of the zone expressed in hours (one hour for each For stations in west longitude, GMT is later; for stations in east longitude, GMT is earlier. At longitude 180, the difference is twelve hours. Accurate time signals are currently broadcast by national observatories in various parts of the world. These signals are of great value to navigators.

GMT is expressed on a twenty-four hour or universal scale, whereas local time is generally indicated on a twelve-hour scale, the twenty-four hour daily period being divided into A.M. and P.M. twelve-hour intervals. Watches are known that are capable of concurrently displaying both GMT and local time. Such GMT timepieces are primarily intended for airline pilots and navigators, and in addition to the usual hour, minute and sweepseconds hands, they include a GMT hand which makes one full revolution per twenty-four hour period.

In a conventional GMT timepiece, the GMT hand operates in conjunction with a movable bezel mounted on the watch casing and graduated in a twenty-four hour scale. The GMT hand is positively geared to the minute and the standard hour hand of the watch, the several hands moving concurrently when the watch is manually set. Thus, assuming that the local zone is on |Eastern Standard Time, GMT will then be five hour later, so that at midnight local time, GMT is 0500 hours. In this instance, the movable GMT bezel must be aligned with its 5 mark opposite the 12, mark on the standard twelvehour scale. But when the wearer moves to a new zone, he must first re-set local time, and then shift the bezel to establish the proper time displacement between local time and GMT.

Accordingly, it is the main object of this invention to provide a timepiece which displays GMT as well as local time, and wherein local time may be set incrementally in one-hour steps, independently of GMT when entering a new zone. Thus there is no need for a movable bezel or for the resetting thereof.

A watch in accordance with the invention is of particular advantage to a navigator, for once the timepiece has been carefully set to GMT on the basis of accurate time signals, it need not be re-set as to GMT as the wearers location changes. Nevertheless, the wearer has the convenience of a local time display, and when a new time zone is entered, the twelve-hour hand may be incrementally retarded or advanced to re-set the local time indication without disturbing the existing GMT indication.

Though watches are known which include a mechanism for setting the hour hand forward or backward to correspond with a given time zone without interfering with the motor mechanism or the setting of the minute hand, such prior art watches generally involve slip clutches and other mechanical systems which include balanced springs. A significant feature of the present invention resides in a positive system of motion transfer to the hands of the timepiece, which eliminates the use of delicate and troublesome motion transmission mechanisms.

More particularly, it is an object of this invention to provide a timepiece having GMT and local-time hands, the local-time hand being operated through a planetary or differential gear system, the arrangement being such that an abrupt shift in the position of the gear coupled to the local-time hand may be effected in either direction without affecting the position or continued movement of the gears to which the GMT hand is coupled.

While the invention will be ldescribed in connection with a `GMT timepiece in which the GMT hand operates along a twenty-four hour scale and the local-time hand operates along a twelve-hour scale, it is to be understood that the principles underlying the invention are applicable to other types of displays. lFor example, the modern traveler has need for a timepiece which indicates both local time and time in another time zone, such as that at his home base.

`It is possible, therefore, in lieu of a GMT hand operating in conjunction with a twenty-four hour scale, to have two twelve-hour hands, both turning with respect to a conventional twelve-hour dial, one hand serving to indicate time at the home base, the other being incrementally adjustable to give time in a local zone without `disturbing the setting of the home-base time hand. Or in its simplest form, a timepiece in accordance with the invention may have a single twelve-hour hand incrementally adjustable to indicate time in a local zone. Common to all timepiece structures in accordance with the invention, is a general purpose -crown for setting the GMT, hour and minute hands in the usual manner, and a special crown for effecting incremental adjustment only of the local-time hour hand.

Briefly stated, these objects are accomplished in a timepiece mechanism provided with a planetary gear system having a sun gear, planet gears and a ring gear, the planet gears being supported by a planet carrier which is linked to the local-time hour hand to be incrementally adjusted. The minute wheel of the watchworks is operatively coupled to the sun gear of the planetary gear system, which in turn causes the planet gears to rotate in an orbital path thereby to turn the planet carrier and hence the local-time hour hand. The minute wheel is also cqupled to a gear train which is arranged to operate the GMT or home base time hour hand, which gear train'is independent of the planetary gear system so that the continued movement of the GMT or home Abase hand is unaffected by the action of the planetary gear system.

The planetary gear system acts as a different mechanism whereby the orbital movement of the planet gears is controlled solely by the sun gear when the ring gear is detented, but when the ring gear is shifted in either direction while the sun gear continues to rotate, the planet gears are advanced or retarded, depending on the direction of ring-gear shift.

In order, therefore, to effect a thirty-degree incremental shift (one hour) in the local-time hour hand, without in any way disturbing the operative coupling between the minute wheel and the sun gear, and without the need for clutches, springs or other means which might interfere with this coupling, the ring gear is caused by an intermittent-motion device to index incrementally in the desired direction.

This is preferably accomplished by a special formation on the outer periphery of the ring gear so that effectively it constitutes the Geneva wheel of a Genevia movement which also includes a Geneva drive engaging the Geneva wheel. This Geneva drive is operated by the special crown of the timepiece through a cam assembly acting as a trigger, such that when this crown is given approximately a full turn in one direction, the Genevia drive causes the ring gear abruptly to produce a thirty-degree advance in the position of the local time hour hand. And when the crown is given approximately a full turn in the reverse direction, it produces a thirty-degree retardation in the position of the local-time hour hand.

For a better understanding of the invention, as well as other objects and further features thereof, reference is made to the following detailed description to be read in conjunction with the accompanying drawing, wherein:

FIG. l is an elevational view of the face of a timepiece having local time and GMT hands in accordance with the invention;

FIG. 2 is a block diagram of the basic components of this timepiece; and

FIG. 3 illustrates, in perspective, the mechanism for operating the hands of the timepiece.

GENERAL. DESCRIPTION Referring now to the drawing, and more particularly to FIG. 1, there is shown the face of a watch in accordance with the invention, the watch including the usual twelve-hour circular dial 10, which is surrounded by a fixed ring 11 graduated in a twenty-four hour GMT scale in which the "24 mark is aligned with the 12 mark on the dial.

A local time display is provided by a local-time hour hand LT which operates in conjunction with the twelvehour dial 10, as does the usual minute hand M and the sweep-seconds hand S. GMT readings are provided by a GMT hour hand GT which operates in conjunction with ring 11. Extending from casing 12 of the watch is a general purpose crown A for simultaneously setting the minute hand M, the local-time hour hand LT, and the GMT hour hand GT. Also extending from casing 12, at a position displaced sixty degrees from the generalpurpose crown, is a special-purpose crown B for incrementally setting only the local-time hour hand LT in discrete one hour steps. The actual positions ofthe crowns is a matter of design.

The setting operation of the timepiece is as follows: On the basis of broadcast time signals or by the use of a suitable time standard, the hour-hand GT is set to GMT time by pulling out general-purpose crown A and rotating it to set minute hand M and hour hand GT to the correct GMT, disregarding the resultant position of the local-time hand LT which is also controlled by crown A. `Crown A is then returned to its normal running position. Now, special-purpose crown B is turned to advance or retard local-time hand LT in one-hour increments until the desired local time is indicated. The operation of crown B in no way disturbs the other hands of the watch which indicate GMT. As the wearer travels to new time zones, instant correction for local time may be made by crown B without affecting the GMT display and without the need for a stand-ard time or master source.

While forming no part of the present invention, it is to be understood that when the general-purpose crown A is pulled out to its setting position, the associated setting mechanism may be arranged in a manner already known in the art to arrest the seconds hand, so that the GMT reading can be set accurately as to seconds as well as to minutes and hours.

Referring now to FIG. 2 showing the basic components of the timepiece in block form, the watch includes the usual cannon pinion 13, which carries the minute hand M and engages a rminute wheel 16. Cannon pinion 13 is driven by the timepiece motor 14, a friction clutch 15 or other known means being provided to permit manual set.- ting of the hour and minute hands by general-purpose crown A. The arrangement is such that when crown A is pulled out, motor 14 is disengaged from the cannon pinion and the crown A is operatively coupled to the minute wheel, whereby the minute and hour hands may be manually set.

Motor 14 may take any known mechanical, electromechanical or electrical form. It may, for example, be in the familiar form of a rewindable mainspring operating in conjunction with a balance wheel and escapement. Or it may be a tuning-fork motor, the vibrations of the fork being converted into rotary motion by a finger attached to a tine of the fork and driving an indexing wheel. An example of a tuning-fork timepiece motor and of a suitable general-purpose setting mechanism to set the minute and hour hands through a crown-operated clutch which disengages the motor from the cannon pinion, is to be found in the Bennett and Mutter Patent 3,262,259, issued July 26, 1966. It is to be understood, however, that the present invention is operable with any known form of watch motor and general-purpose time-setting mechanism.

Secured tothe shaft of minute wheel 16 and turning therewith is a transmission gear 17 which is operatively coupled both to the input of a gear train 18 and to one input of a planetary gear system 19. The output of gear train 18 operates the GMT hour hand GT, the gear ratio of the train with respect to the rate of rotation of the minute wheel being such that the hour hand GT makes one full revolution per twenty-four hour period.

Planetary gear system 19 is a differential device con. stituted by a sun gear, planetary gears carried by a planet carrier, and a ring gear, the sun gear forming one input of the system and the ring gear the other, the planet carrier providing the output which operates the local-time hour hand LT. Transmission gear 17 is operatively coupled to the sun gear of this system, whereas the ring gear is operatively coupled to the special-purpose crown B through an intermittent-motion device 20.

The ring gear, which is the second input of the planetary gear system, is normally detented, and the gear ratio of this system is such that the local-time hour hand is caused to make one full revolution per twelve-hour period. When, however, intermittent-motion device 20 is operated by turning the special-purpose crown B in a particular direction, then the ring gear of the planetary gear system is caused to shift abruptly to an extent effecting a thirty-degree shift in the position of the planet carrier and hence the local-time hand LT, to advance or retard this hand in a one-hour step.

Thus in operation, the minute and the local-time hour hands and the GMT hour-hand are set by crown A, which essentially serves to set the minute and GMT hands to the correct GMT. The resultant position of the local-time hand LT is then corrected by the special-purpose crown B which incrementally shifts the local-time hand one hour at a time until it indicates time in the local zone. Thereafter, no further correction is necessary until such time as one moves into a new time zone, at which point the local-time hand is re-set without alecting the existing and correct setting of the GMT hand.

The local-time incremental setting mechanism is of particular value in conjunction with a two-zone timepiece which incorporates a calendar mechanism, for then the change of date may be made to occur in accordance with local time at about midnight.

THE TWO-ZONE SETTING MECHANISMS Referring now to FIG. 3, the details of the components described generally in FIG. 2 will now be set forth.

It will be seen that minute hand M is attached to a Support tube 30 mounted on cannon pinion 13, which pinion intermcshes with minute wheel 16. The manner in which the cannon pinion is driven by the timepiece motor and in which the minute wheel is manually set by the general-purpose crown A to adjust the position of the various hands of the timepiece, was explained in connection with FIG. 2, and need not, therefore, be repeated.

It will also be seen that minute wheel 16 is mounted on a shaft 16A connected to transmission gear 17. Transmission gear 17 intermeshes with the input gear 21 of the gear train 18, which further includes gears 22 and 23, the latter engaging an output wheel 24. The gear ratio of the train is such that Wheel 24 makes one full revolution per twentyfour hour period. The GMT hand GT extends from a tube 25 mounted on output wheel 24, and hence makes one full revolution in the course of a twenty-four hour period.

Transmission gear 17 is also operatively coupled to the sun gear 26 of the planetary gear system, generally designated by number 19, which system further includes a set of planet gears 27 supported on a common planet carrier 28, the planet gears engaging the sun gear, so that as the sun gear rotates, the planet -gears move in an orbit thereabout to turn the planet carrier. Encircling planet gears 27 is a ring gear 29 whose internal teeth 29A engage the teeth on the planet gears.

Mounted on planet carrier 28 is a support tube 31 for lthe local-time hand LT. Since the sun gear 26 represents one input of the planetary gear system, and the other input is ring gear 29, the gear ratio of this dilerential mechanism is made such that when ring gear 29 is detented, the planet carrier 28 is caused to make one 360 revolution during each twelve-hour interval, thereby turning the local-time hand LT at the proper rate.

The tube 30 for minute hand M telescopes within tube 31 for the local-time hand LT, which in turn is received Within tube 25 for the GMT hand GT, so that the various hands have a common axis and turn concurrently. While the support tube and the related drive means for the sweep-seconds hand are not shown, these are conventional, the seconds-hand shaft being received Within the minutehand tube.

In order to effect an incremental thirty-degree change in the position of local-time LT to effect zone correction, it is necessary to eiect a shift in the position of ring gear 29, which is the second input of the differential gear system, the first being the sun gear. This is accomplished by a Geneva mechanism whose operation in no way disturbs the operative coupling between minute wheel 16 and sun gear 26, and without the need for clutches or springs.

The Geneva mechanism, which is the preferred form of the intermittent motion device shown in FIG. 2, includes a Geneva wheel constituted by equally spaced sets of Geneva teeth formed on the outer periphery 29B of ring gear 29, these sets of teeth being successively engaged by a single set of teeth formed on the Geneva drive 32. Thus ring gear 29 of the planetary gear system has a dual function, for it also serves as a Geneva Wheel. The arrangement s such that when Geneva drive 32 makes a full turn, it causes ring gear 29 to index clockwise or counterthereby causes the local hour-hand LT on planet carrier 28 to advance or retard thirty degrees.

The Geneva mechanism is driven by special-purpose crown B whose stem 33 terminates in a clutch wheel 34 having an annular -groove which is engaged by a dog (not shown) serving to secure the axial position of the clutch wheel. Clutch Wheel 34 is coupled by a gear 36 to an index override gear assembly. This assembly includes an upper disc 37 which meshes with gear 36 and is provided with a pair of opposed arcuate slots 37A and 37B. Also provided is a lower disc 38 having a pair of diametrically opposed pins 38A and 38B which enter slots 37A and 37B in the upper disc. Thus when special-purpose crown B is turned in either direction, the upper disc 37 of the override assembly is caused to turn, but the lower disc is not engaged until the pins 38A and 38B thereon make contact with the ends of the elongated slots 37A and 37B in the upper disc. This arrangement provides the necessary free travel in the linkage as indexing occurs, for the special-purpose crown B and its stem 33 may not be free to rotate as a result of friction introduced by O-ring seals (not shown) which may be used n conjunction with the crown for purposes of waterproofing.

The index override gear assembly is coupled to the Geneva drive 32 by way of a cam assembly which includes an oval-shaped index cam 39 whose surface is engaged by a Geneva index spring 40, the cam having a pin Y 39A extending from the undersurface thereof through an clockwise, depending on the direction of the turn, and

arcuate slot 32A in Geneva drive 32. This elongated slot in the Geneva drive, which operates in conjunction with pin 39A in the cam, provides a symmetrical bi-directional indexing action.

Cam 39 is provided with a square hole 39B within which is received the square head of a post 41 secured to a gear 42 which is engaged by the teeth in the lower disc 38 of the override gear assembly. Thus when the special-purpose crown B is turned to cause rotation of lower disc 38, this eiects rotation of gear 42 and of post 41 thereon, thereby operating index cam 39.

The Geneva index spring 40 in conjunction with index cam 39 serves two purposes. First, it provides a jump or trigger indexing action of local-time hand LT, for when the oval-shaped index cam 39 is turned to a position releasing tension on the spring, the cam pin 39A acts abruptly to actuate the Geneva drive 32 to produce the desired incremental change in the position of local-time hand LT. Second, this arrangement provides a hard turn action in either direction, for in the non-operative position of cam 39, index spring 40 which engages the end of the carn is under maximum tension. The positive positioning of the Geneva wheel assures synchronization of the local-time hand LT with the other hands in the timepiece, regardless of the amount one chooses to correct its readlng.

Thus minute wheel 16 by way of its transmission gear 17 simultaneously drives the gear train 18 for turning the GMT hand GT and the planetary gear system 19 for turning the local-time hand LT, and when an incremental change is made in the position of the local-time hand by shifting the ring gear in the planetary gear system, this in no way affects the operation of the gear train for the GMT hand. In the event one desires to have a twelve-hour hand to display time at a home base, rather than a GMT hand, the home-base hour hand may be used in conjunction with a gear train having a gear ratio providing the necessary twelve-hour movement. Or one may dispense entirely with a GMT or home-base time hand in the timepiece and simply use the zone-setting mechanism with a single hour hand. A timepiece of this type is useful for the frequent traveller, for while it gives him a conventional time dis- Iplay, whenever he enters a new time zone he has merely to turn crown B in the appropriate direction to abruptly index the hour hand without otherwise aiecting the setting.

What we claim is:

1. In -a timepiece having a minute hand shaft and means to effect rotation thereof, a mechanism for operatively intercoupling said minute hand shaft to an hour hand to turn said hand to indicate time and to permit incremental shifting of the position of said hand in either direction to set said hour hand, said mechanism comprising:

(A) a planetary gear system constituted by a sun gear, at least one planet gear supported on a planet carrier and engaging said sun gear, and a ring gear engaging said planet gear,

(B) means operatively coupling said minute hand shaft to said sun gear to cause said planet gear to move in an orbit about said sun gear and thereby to cause said planet carrier to turn 360 each twelve-hour period,

(C) means linking said hour hand to said planet carrier to turn therewith, and

(D) an intermittent motion device operatively coupled to said ring gear to shift the ring gear in either direction to an extent effecting .a shift in the position of said planet carrier in 30 increments.

2. In a timepiece, as set forth in claim 1, further including fast action means to effect abrupt actuation of said intermittent motion device.

3. In a timepiece, as set forth in claim 1, a second hour-hand to indicate Greenwich mean time, and a gear train operatively coupling said minute hand shaft to said second hour-hand and having a gear ratio to' cause said hand to make one full turn cach twenty-four hour -period independently of the operation of the first hour-hand.

4. In a timepiece, as set forth in claim 1, a second hourhand to indicate time at a home station, and a gear train operatively coupling said minute hand shaft to said second hour-hand and having a gear ratio to cause said second hour-'hand to make a full turn each twelve-hour period independently of the operation of said first hour-hand.

5. In a timepiece, as set forth in claim l, wherein said means to effect rotation of said minute hand shaft is a tuning-fork motor.

6. In a timepiece, as set forth in claim 2, wherein said fast action means is constituted lby a spring assisted carn mechanism which actuates said intermittent ymotion device.

7. In a timepiece having a`minute hand Ashaft and a minute hand thereon and meansl to effect rotation thereof, a mechanism for operatively intercoupling4 said minute hand shaft to an hour hand to turn said hand to indicate time and permit incremental shifting of the position ofy said hand in either direction to setsaid hand for a given time zone, said mechanism comprising:

(A) a planetary gear system constituted by a sun gear, at least one planet gear supported on a planet carrier and engaging said sun gear, and a ring gear having internal teeth engaging said planet gear,

(B) means operatively coupling said minute hand shaft to said sun gear to cause said planet gear to move i11- an orbit about said sun gear and thereby to cause said planet carrier to turn 360 each twelve-hour period,

(C) means linking said hour hand to said planet carrier to turn therewith,

(D) a Geneva mechanism operatively coupled to said ring gear to shift the ring gear in either direction to an extent effecting a shift in the position of said planet carrier, said mechanism including a Geneva wheel constituted by spaced sets of teeth for-med on the outer periphery of said ring gear, and a Geneva drive index gear engaging said Geneva wheel to effect intermittent motion of said ring gear in either direction, and

(E) manually-operated Ameans coupled to said Geneva drive index gear to turn same in a direction effecting the desired intermittent motion.

8. In a timepiece, as set forth in claim 7, further including a general-purpose crown operatively coupled to said minute hand shaft to set said hour and minute hands simultaneously, and wherein said manually-operated means is provided with a special-purpose crown operatively connected to said Geneva mechanism to effect incremental setting of the hour hand.

9. In a timepiece, as set forth in claim 8, wherein said f Geneva drive index gear is operated by said special-purpose crown through a spring-biased index cam assembly v I to effect jump-indexing thereof. 30

10. In a timepiece, as set forth in claim 9, wherein said special-purpose crown is coupled to said index cam assembly through an override assembly to provide free travel.

11. In a timepiece, as set forth in claim 7, further including a Greenwich mean-time hand, and a gear train References Cited UNITED STATES PATENTS v3,184,909 5/1965 Lohfetal. st- 85.5 3,358,437 12/1967 Burg 5s-43 STEPHEN J. ToMsKY, Primary Examiner EDITH C. SIMMONS, Assistant Examiner US. Cl. X.R. 58-43, 85.5 

